Traumatic brain injury
What is the connection between a singular traumatic brain injury (TBI) and long-term loss of cognitive function, i.e., processing and memory? If the connection is tenuous, why is there continued focus on TBI?
—Felix N. Chien, DO, Newport Beach, Calif.
The effects of any given TBI depend on several important factors: (1) the premorbid cognitive status of the patient; (2) the age of the patient; (3) the type of head injury; e.g., low vs. high velocity and the presence of angular velocity, which increases the effects of shear injuries on axons, leading to diffuse axonal injuries; and (4) management of the head injury. The post-traumatic deficits also show a relationship to the type and localization of the injury. The relative “silent” areas (e.g., prefrontal and occipital) may not show abnormalities if there are very focal injuries. With diffuse axonal injury, there is more widespread shearing of axons, which may not always be readily identifiable on the MRI. However, this can cause significant disruption of cognitive function, including memory and processing. Last, the continued focus on TBI results from the fact that so many cases are preventable if people avoid unprotected sports, unprotected driving, and the effects of alcohol and drugs.
—Jay E. Selman, MD (126-9)